Electric starting mechanism for internal combustion engines



Dec. 14, 1965 K. PREECE ETAL ELECTRIC STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed June 19, 1963 United States Patent 3,223,863 ELECTRIC STARTING MECHANISM FOR INTERNAL CQMBUSTION ENGINES Kenneth Preece and Roy Price Bowcott, Solihull, England, assignors to Joseph Lucas (Industries) Limited. Birmingham, England Filed June 19, 1963, Ser. No. 289,112 Claims priority, application Great Britain, June 25, 1962. 24,269/ 62 3 Claims. (Cl. 310--75) This invention relates to electric starting mechanism for internal combustion engines, and of the kind comprising in combination an electric motor, a pinion mounted on an extension of the rotor shaft of the motor, a solenoid for moving the pinion axially on the shaft into engagement with a toothed wheel of the engine, and a motor controlling switch arranged to be closed when the solenoid armature has moved to its fullest extent under energisation.

The object of the invention is to provide such mechanism in an improved form.

According to the invention mechanism of the kind specified comprises a rockable lever for transmitting movement from the solenoid to the pinion, one end of the lever being operatively connected to the pinion and the other end being operatively connected to the solenoid armature, and resilient means acting on a part of the lever removed from the pinion whereby in the event of tooth to tooth engagement of the pinion and engine wheel the solenoid armature can move to a position to close the motor controlling switch against the action of said resilient means.

In the accompanying drawings,

FIGURE 1 is a part-sectional side elevation of one example of an electric starting mechanism in accordance with the invention.

FIGURE 2 is an end view of the example shown in FIGURE 1 with parts removed for the sake of clarity, and

FIGURE 3 is a fragmentary view of part of the mechanism shown in FIGURE 1.

Referring to FIGURES 1 and 2 of the drawings there is provided a motor casing 1 in which are mounted field coils 2 and a rotatable armature 3, the shaft 4 of which is extended at one end and is supported in a bearing 5 mounted in a housing 6 secured to the motor casing. A portion of the shaft is provided with a quick pitch screw thread which is engaged by a complementarily screw threaded sleeve 7 formed integrally with the outer member of a unidirectional clutch 8. The inner member of the clutch is formed integrally with a pinion 9 which together with the clutch and the sleeve can be moved axially along the shaft so that the pinion can engage with a toothed wheel 16 of an engine with which the starting mechanism is associated.

Surrounding the sleeve and fixed relative thereto, is a collar 11 which defines an annular channel 12. Located in this channel, at diametrical opposite points, are a pair of abutments 13 which are secured to a forked end of a lever 14 which is pivoted at its midpoint about a pin 15 mounted in the housing. The other end of this lever is also forked and is connected to means which will now be described.

On the housing is mounted a solenoid which includes a winding 16 and an armature 17 which is spring loaded in a direction towards the housing by an armature spring 18. Extending through the armature is an axial bore in which is accommodated a control rod 19 which extends beyond the armature towards the housing. The rod is resiliently restrained from movement relative to the armature towards the housing by a control spring 20 which bears against an abutment plate 21 secured to the arma- "ice ture and furthermore, mounted on the exposed end of the rod is a collar 22, and also mounted thereon is a thrust plate 23 which is urged towards the collar 22 by a lost motion spring 24. The collar 22 and the plate 23 define a gap in which is mounted the other forked end of the lever 14.

Mounted on the end of the solenoid remote from the housing is an electric switch housing 25 in which are mounted a first pair of fixed contacts 26 which are arranged to be bridged by a movable contact 27. The movable contact 27 is connected to a hollow push rod 28 which is arranged to be moved, so that the contacts 26 are bridged, by. the armature 17 of the solenoid. Moreover also within the housing are a second pair of fixed contacts which are not shown but which are arranged to be bridged by a movable contact 29 which is connected to a push rod 30 accommodated co-axially within the push rod 28. The push rod 30 is arranged to be moved, so that the second pair of contacts are closed, by the control rod 19. The first pair of contacts 26 are connected so that when they are bridged only a part of the field system of the motor is energised whilst the second pair of contacts 26b are connected so that when they are closed the rest of the field system of the motor is energized.

The arrangement is such that, when the solenoid winding is energized, the armature will be drawn into the solenoid causing the lever 14 to be moved about its pivot to move the pinion into engagement with the toothed wheel. During this movement a slight rotary movement will be imparted to the pinion owing to the action of the quick-pitch screw-thread. When the armature nears the end of its movement both switches will be closed to energi-se the motor to rotate the pinion and hence the toothed wheel of the engine. When the engine has started the solenoid winding is de-energized and the armature will be moved, by the action of its spring, to open both switches to de-energise the motor. Further movement of the armature will result in disengagement of the pinion from the toothed wheel and this will be aided by the action of the quick-pitch screw-thread. If the solenoid is de-energised before the engine has started the friction between the pinion and toothed wheel may be too great to permit disengagement, however, the lost motion spring will compress to allow the solenoid armature to move to open both switches and so de-energise the motor.

If after energisation of the solenoid winding tooth to tooth engagement of the pinion and toothed wheel takes place, then the armature will move to close the first pair of contacts, and so energise a portion of the field windings of the motor, against the action of the control spring which latter spring will then effect engagement of the pinion and toothed wheel when the motor rotates at low speed. When engagement is completed the end of the control rod will bear upon the end of the push rod 30 to effect closure of the second pair of contacts and so cause the motor to rotate at full speed.

If desired the second pair of contacts, the movable contact 29 and the push rod 30 may be omitted in which case the first pair of contacts 26 are arranged, when bridged by the movable contact 27, to efiect energisation of the whole of the field system of the motor so that the latter will rotate at full speed. It being understood that, in the event of tooth to tooth engagement of the pinion and toothed wheel, the armature will be able to move, to cause the contacts 26 to be bridged, against the action of the control spring 20.

In this example the control rod 19 is fixed relative to the solenoid armature 17 and only a single pair of contacts are provided in the switch housing 25 these being so arranged to be closed by a movable contact (not shown) which is movable by the armature 17 when the latter nears the limits of its inward movement. Moreover the lever 14 is of hairpin form having its free ends pivotally connected to an abutment plate 31 which is mounted on the sleeve 7 to permit of relative angular movement but not axial movement. Furthemore the limbs of the lever are interconnected by a cylindrical bar 32, which is slidably mounted in a projection 33 formed on the housing 6, and which is loaded by a spring 34, in a direction away from the casing onto an adjustable pivot 35.

The function of the spring 34 is similar to that of the control spring 20 of the first example, in that, if tooth to tooth engagement of the pinion and toothed wheel occurs then the armature is allowed to move inwardly to close the switch. This being permitted by compression of the spring 34 which, when the motor starts to rotate, effects engagement of the pinion and toothed wheel.

Having thus described our invention, What we claim as new and desire to secure by Letters Patent is:

1. Starting apparatus for an internal combustion engine comprising, an electric motor, a rotor shaft ext-ending from said motor, an axially movable pinion mounted on said shaft into engagement with a toothed wheel of the engine to be started, means for connecting said pinion with said shaft so that when the shaft is rotated rotary motion will be imparted to said pinion, a lever having one end operatively connected to said pinion so as to move said pinion axially on the shaft, an electromagnet having an armature operatively connected to the other end of said lever, resilient means acting intermediate the armature and said other end of the lever, said resilient means being arranged to be stressed when a tooth of the pinion engages end-to-end with a tooth of the toothed wheel to allow the armature to move to its fullest extent when the electro-magnet is energised, a first motor controlling switch disposed to be closed by the armature when the latter has moved to its fullest extent, the closing of said first motor controlling switch being arranged to energize the motor at low power, and a second motor controlling switch disposed to be closed by said other end of the lever, said second motor controlling switch being arranged to energise the motor at full power, so that in the event of end-to-end engagement occuring the motor will be energised at low power to cause the pinion to be moved angularly to clear said engagement whereupon the resilient means will move the pinion into full engagement with the toothed wheel and the second motor controlling switch will be closed to energise the motor at full power.

2. Starting apparatus as claimed in claim 1 including an armature spring for loading the armature of the electro1nagnet against the action of the electro magnet, said armature spring serving to effect disengagement of the pinion and toothed wheel when the electro-magnet is de-energized.

3. Starting apparatus as claimed in claim 2 including a lost motion spring positioned intermediate said other end of the lever and the armature said spring allowing the armature to move under the influence of the armature spring when the electro-magnet .is tie-energised so as to open said first and second motor controlling switches in the event of the armature spring being unable to move the pinion out of engagement with the toothed wheel.

References Cited by the Examiner UNITED STATES PATENTS 2,302,687 11/1942 Dyer. 2,716,895 9/1955 Antonidis 290-38 2,839,935 6/ 1958 Hartzell.

ORIS L. RADER, Primary Examiner.

MILTON O. HIRSHFIELD, Examiner. 

1. STARTING APPARATUS FOR AN INTERNAL COMBUSTION ENGINE COMPRISING, AN ELECTRIC MOTOR, A ROTOR SHAFT EXTENDING FROM SAID MOTOR, AN AXIALLY MOVABLE PINION MOUNTED ON SAID SHAFT INTO ENGAGEMENT WITH A TOOTHED WHEEL OF THE ENGINE TO BE STARTED, MEANS FOR CONNECTING SAID PINION WITH SAID SHAFT SO THAT WHEN THE SHAFT IS ROTATED ROTARY MOTION WILL BE IMPARTED TO SAID PINION, A LEVER HAVING ONE END OPERATIVELY CONNECTED TO SAID PINION SO AS TO MOVE SAID PINION AXIALLY ON THE SHAFT, AN ELECTROMAGNET HAVING AN ARMATURE OPERATIVELY CONNECTED TO THE OTHER END OF SAID LEVER, RESILIENT MEANS ACTING INTERMEDIATE THE ARMATURE AND SAID OTHER END OF THE LEVER, SAID RESILIENT MEANS BEING ARRANGED TO BE STRESSED WHEN A TOOTH OF THE PINION ENGAGES END-TO-END WITH A TOOTH OF THE TOOTHED WHEEL TO ALLOW THE ARMATURE TO MOVE TO ITS FULLEST EXTENT WHEN THE ELECTRO-MAGNET IS ENERGISED, A FIRST MOTOR CONTROLLING SWITCH IS DISPOSED TO BE CLOSED BY THE ARMATURE WHEN THE LATTER HAS MOVED TO ITS FULLEST EXTENT, THE CLOSING OF SAID FIRST MOTOR CONTROLLING SWITCH BEING ARRANGED TO ENERGIZE THE MOTOR AT LOW POWER, AND A SECOND MOTOR CONTROLLING SWITCH DISPOSED TO BE CLOSED BY SAID OTHER END OF THE LEVER, SAID SECOND MOTOR CONTROLLING SWITCH BEING ARRANGED TO ENERGISE THE MOTOR AT FULL POWER, SO THAT IN THE EVENT OF END-TO-END ENGAGEMENT OCCURING THE MOTOR WILL BE ENERGISED AT LOW POWER TO CAUSE THE PINION TO BE MOVED ANGULARLY TO CLEAR SAID ENGAGEMENT WHEREUPON THE RESILIENT MEANS WILL MOVE THE PINION INTO FULL ENGAGEMENT WITH THE TOOTHED WHEEL AND THE SECOND MOTOR CONTROLLING SWITCH WILL BE CLOSED TO ENERGISE THE MOTOR AT FULL POWER. 